For many entrepreneurs, the billion dollar valuation or exit, is the non-negotiable target they set for themselves. As of 2015, there are just over 1,800 (known) dollar billionaires in the world, with a combined wealth of over $7 trillion-which is growing fast (the same list had a combined wealth of ‘just’ $3.6 trillion five years ago). Mitch Cohen (Vice Chairman of PwC) along with his colleague John Sviokla conducted the first-ever study on self-made billionaires,…